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:N. J. CONRAD PRIMARY CUTjOUT Feb. 12, 1929.`

3 'sheets-Sheet. 5

Q lginal Filed March '7, 1919 5 tion system'. Primary circ from electrical sub-stations, stations on a high potential line, immediate vicinity and supply current y il NIGHLAS J. ONRAD, UF 'Wfl Original Ll'a. 1,466,423,

trical circuits.

'lill aussen] clatedlng'ust ad, i923, Serial No. ll, ledliltarcli 7, 1919. Application for reissue lleil November 16,'1928.

My invention relates to cut-outs for eleyc- More particularly my invention relates to an improved cut-fout for the primary circuits service transformers electrical distribuuits usually extend or transformer out over the of an tor'light and power distribution. Such circuitsordinarily carry potentials ranging from 1,00() to 15,00

Switching in this diilicult by the moderately high voltage,

volts. type of circuit is made the requirement for exposed overhead installation, which precludes large or complicated disconnect-i ng means, and the large number of such circuits in the usual distribution net which prohibits the use of costly apparatus.

A form ot connecting means used extensive-lv in these circuits is the ordinary type of plug ries a with te and socket cut-out,v wherein the plug carifusible link adapted to have connection rin'inals in the socket, which terminals arefconnected to the line. This provides a simple the line, and it is sub] ingl these disturbanf andinexpensive construction but does not aiiord the desired security against injury,

the adjacent apparatus, elievingr disturbances on feet to d amage in relieves. As' ordinarily cony structed, this .type of cut-out is diilicult and dangerous to operate,

as the entire explosive force of blowing oi the fuse by plugging into a sliort-circuited lin into the hand of the av is end o e is discharged directly operator. The operator 1s generally below or at one side of the cut of the fuse--if he plugs discharged liarmlessly -out ot the other f the socket, away from the point of insertion of the plug, and away from the position of the operator, with a consequent 1inpossibility of burning tli )ect is to provide an device in the cut jury to thc cut-out. more provides a e operator. Another oba improved torni of fuse out which will quickly relieve any disturbance on the line without in- My invention furtherdurable` weather-proof structure, particularly adapted for installato the sei-iai no. 319,395.

'tion on a pole top or cross-arm, in suitable relation to the' transformer 'or other apparatus to be disconnected.

In the accompanying drawings, I have il-` Figure 4l is avertical sectional view sho-winnl the plug and socket members in operative association; V

Figure 5 is a transverse sectional view taken on theline 5 5 of Figure 4;

Figure 6 is a transverse sectional view taken on the line 6-6 of Figure 3;

taken on the line 7-7 of Figure il;

Figure 8 is a detail view showing the disposal of the fusible link and high resistance wire in the surrounding cork;

Figure 9 is an elevational view of the releasable end cap, which closes ofi the bottom ot the fuse; and,

Figure 10'is a cross-sectional view of the same.

In Figure' 1 I have illustrated a typical installation of my improved cut-out upon the cross-arm l of a transformer pole, or other point of disconnection The cutout mainly comprises an outer socket member 2, which carries the main Contact terminals included in the line 3-3, and the removable plug* member 4, whichbears the fuse device l'orinterrupt-ing the circuit in case-ot overload'or short circuit. It will be noted that the plug member 4 adapted for in-` Figure 7 is a transverse sectional view to the type of fuse employed, as I shall pres- Y ently describe.

The socket member 2 preferably consists .A

of a tubular member of insulation formed ,with two small circumferential bea-ds 5-5, between which engages clamp G. The

clamp 6 is gripped tightly about the body of the socket 2 by a bolt 7, extending tion. The upper conducting ring through the sides of the clamp. The ends of the clamp 6 are' bent laterally to form feet 8-8, which are screwed or bolted to the cross-arm 1, as indicated at 9. These feet are also bent diagonally to the body of the clamp to incline the lower end of the socket member 2 down beneath the crossarm 1, and into the clear. It is from the lower end of the socket 2 that all discharges caused by the violent blowing of the fuse are relieved, and it will be noted that this end is directed away from any position the operator, or any part of his body,

may assume when iu the act of inserting the plug member.

Referring to the detailed construction of socket member 2,v as shown rin Figures 2 and 4, it will be noted that this member is in the form of a hollow sleeve 11, having an enlarged head 12, which sleeve is provided with contact terminals at the upper and lower ends of a central bere for reeciving the plug member 4. This socket member is preferably constructed of an insulating material, such as balelite or bakelized vfibre. The contact terminals are each madein the form of short sleeves 13 and'14, which are slotted at numerous points as indicated at 15 to afford a greater resiliency of contact with the ferrules on the fuse member of the plug 4. lThese Contact sleeves depend from two large conducting rings 16 and 17, in which the sleeves are soldered. The conducting rings 16 and 17 are held in their respective ends of the sleeve member 11 by engaging upon the shoulders 18-18. The shoulders 18 are formed by making the intermediate portion of the bore of the sleeve of a slightly smaller diameter than the upper end, and the lower end of a diameter slightly smaller than the intermediate por- 16 is held to its shoulder by a screw 21 threading diagonally through the ring and engaging the inner surface of theK sleeve, and the lower conducting ring is similarly held by a diagonal screw 22, which is accessible through the open bottom of the sleeve 11. In Figures 4 and 5 I have illustrated a slightly different method of retaining the lower conducting ring 17 upon its shoulder 18. A groove is formed about the circumference of the ring 17, and matches with a similar groove inV the sleeve 11, as indicated at 23, and in these grooves is confined a ring 24 which is split transversely as indicated in Figure 5.

`A screw 25 threading diagonally up thru the bottom of the ring 17 may be employed for spreading the split ring 24 out into engagement in both grooves. In placing the -contact ring 17 and the split ring 24 within the sleeve 11 the twoV are merely pushed down from the top of the sleeve, the resiliency of the split ring permitting it to be sprung inwardly into the groove in the con- .the threaded tact ring, until the split ring engages `with the groove 23 `in the sleeve 11, whereupon it springs outwardly under its own resiliency and locks the contact ring in place.

The line connections are made byV extending one side of the line 3 up thru `a hole 26 in the enlarged head 12 and into the interior of the socket where it is soldered in a hole 27 in the upper conducting ring 16. The other side of the line 3 enters the bottom of the socket 2 through a hole 28 and passes up through a groove 2S),

'and is soldered in a hole 31 in the lower conducting ring 17. The upper faces of both conducting rings 16 and 17 are made conical, to aid in centering the plugmember 4, when the latter is being inserted into the socket 2.

Referring to the detailed construction voiE the plug member A4,as shown in Figui-e 3, the handle 32, which is of bakelite, rubber, or some suitable insulation, is formed with a depending hood 33, which is adapted to set downover the head 12, on the end of the socket 2, thereby excluding moisture and shielding the operators hand from any possible injury in pulling or inserting the plug. A polygonalmetallic insert 34 is molded in the handle 32, and is tapped for receiving end 35 0f the conducting stud 36. The stud 36 is threaded externally for the engagement of the upper Contact ferrule 37 on the fuse 38. A lock washer 39 is interposed between thestud 36 and the tapped insert 34, to bind this threaded connectionl so that the ferrule 37 will unscrew first from the stud 36 in taking the fuse apart.

The fuse which I employ in my improved cut-out is novel in construction and operation, 'combining the advantages characteristic of the spring and expulsion types of fuses. When the abnormal condition on the line is of minordegree, the spring action of the fuse will alone sutce to extinguish the arc generated by the melting of the fusible link. When the explosive condition is pronounced, as during a short circuit or heavyl overload, the expulsion action of the fuse eifectually extinguishes the arc by expelling the lower contact member from the end of the fuse case andblowing the arc out. This will be more apparent after a detailed description of the construction and operation of the fuse.

Referring again to Figure 3, the fuse 38 is enclosed in a tube 41 'of fibre or bakelite, the upper end of which is secured to the ferlule 37. At its lower end, the outer surface of the tube 41 is machined down to a reduced diameter to receive the lower ferrule 42, which lies flush with the surface of the tube 41. Inclosed in the tube 41 is a large stranded conductor 4 3, connecting the upper ferrule 37 with the fusible link, which I shall presently describe, and a tension spring'44 which functions to separate the ends of the fusible link when the latter melts under abnormal'current flow. Both the conductor 43 and the spring 44 have their upper ends secured'in holes in a stem member 45, which is an extension of the stud 36, as indicated at 46. At its lower end the stranded conductor 43 is soldered 'into a hole in the" end of afstem 47, and the tension spring 44 is similarly secured in a transverse hole in the stem; A link or terminal member 48 threads into the bottomiofV the stem 47, land extends down into a cork 49, or similar heat confining block. This terminal memberfis formedl with a square shank por tion 48l for grasping with a tool to facilitate threading the terminal member into the stem 47. In the cork 49 the terminal mem'- ber has connection with a fuse wire 51, of V prescribed current carrying capacity, and a small high resistance-wire@ of large tensile strength. These are clearly shown in Figure 8. The` end of the terminal member 48 is flattened out into the shape of an' eye, and linking this eye to asimilar eye in the end of a large conducting wire 53 is the fuse wire 51 and tensile wire 52. The tensile wire 52 is arranged to bear the mechanical stress imposed by the tension of the spring 44. The conductor 53 extends out of the cork 49 and down thru a hole in the end cap l54 where it has connection on the outside thereof by a screw 55. turned up inthe form of a thimble, and is provided with vertical slotsspaced about its periphery to secure a spring `fitin the lower end of the ferrule 42. The reaction of the tension spring 44- is borne by the upper edge of the cap 54A abutting the lower edge of the insulating tube 41.

A notable feature of this fuse construction is that the action on violent blowing is a combination of spring action and expulsive action.

For illustration, consider the fuse as blowing on a. dead short circuit or very heavy overload. y The fusible wire 51 will blow and the tensile .wire 52 at about the same instant, whereupon the terminal member 48 will be jerked outof the cork 49 up into the upper end of the tube 41. Under an `ordinary overload condition the rapidly enlarging gap and the tendency of the cork 49 to confine the arc drawn from the tip of the teri'ninal 53 would suflicc to extinguish the arc before the terminal 48 had traveled any considerable distance, but if the blowing is violent the cxtreme temperatures generated by the are will instantly develop an explosive air pressure in the tube 41. As a consequence, the entire group of elements, consisting of the cork 49, the terminal and the end cap 54, will be blown out of the end of the tube 41 and the arc with them.

For the purpose of giving a visual indica- This'end cap tion that the fuse has been thus blown, I attach an indicating strip 57, which is preferably in the form of a long Strip of celluloid, tothe bottom of the end cap 54, by the screw 58, and extend this strip down out of the bottom of the socket 2. The absence of this strip indicates that the fuse has been violently blown. To determine whether the fuse element is still intact, or has fused Vunder light overload without'expelling the end cap, it is only necessary to slightly pull this indicating strip 57; if the fuse is still intact the tension of the spring 44 will be felt, otherwise the end cap 54'can be drawn out of the bottom of the fuse.

To renew the fusible link, the tube 41 is {i1-st removed by unserewing the upper ferrule 37 from the stud 36. The fusible link 51, the tensile wire 52, and, if necessary ythe terminal members 4.8 and 53 are then replaced and tire cork '49 is stripped over the terminal members link and tensile Wire. The conductoror terminal 4member 53 is originally quite long, and thus it may be .threaded down thru the tube 41 and thru the central hole in the end cap 54. The conductor 453 is then drawn up to apply tension to the spring 44 and is fastened to the screw 55, andA its end cut off.

The provision of the cork49 renders the fusible link 51 immune to atmospheric in- `fiuences, which is an important factor in-air fuses, The fusible link is doubly protected in this respect by the cork 49, thenatural resiliency of which makes it snugly embrace the terminal members 48 and 53, and also by the end cap 54 which closes the lower end of the tube 4l against the entrance of atmospheric variations. The cork 49 is 'arranged to tquite closely in the tube 41, and this tends to isolate the area above the cork from atmospheric influences, whereby 'the possibility ofl these influences penetrating thru to the fusible link is still further reduced.

` A further utility of the-cork is that of assisting in the extinctionof the arc byclosing the upper hole as vsoon as the upper terminal member has Withdrawn, and thus either sti-angling the arc or closely confining it to surround the fusible i to the tip of the lower terminal memberlil.' f

Due to )its close lit in the tube 41, the cork receives the full force of the explosive air pressure developed in the tube, Vand drives everything before it when it is expelled.

From the foregoing description, ilV will. be apparent that Athe expulsion action of the fuse has particular cti-operation with the general construction` and mounting of the cut-out. On expulsion action the fuse rc quires imnlediate and clear access to the ati'nospherc, and the only practical provision for thisis by leaving one end of the socket entirely open. This end is conveniently made the lower end, as there are no are exo tinguishing liquids to be lost, and a satisfac.

tory weather-proof construction results. The oblique mounting of the cut-out directs the discharge of the fuse down and away from `the position of the operator, and thus there is` practically no possibility of the operator being burned by this discharge.

While I have shown and described my invention with reference to the particular details of construction of one embodiment, it is to be understood that the invention may appear in different forms, and with numerous modifications and variations such as will suggest themselves to one skilled in the art, but I consider all such modifications and variations to be included within the scopev of my invention.

I claim:

1. In a cut-out, a plug member and a cooperating socket member, said socket member comprising a sleeve of insulation open v at both4 ends and having stationary contacts opening,

therein, the plug member being insertable into one end, of the sleeve and the' other end of Saidsleeve having a straight unobstructed said plug member Acomprising a fuse having terminal contacts for engagement with said stationary contacts and a terminal member free to be expelled through the straight vunobstructed opening of the socket member by blowing of the fuse.

2. In a cut-out, a socketmember comprising a sleeve `of insulation open at both ends and having stationary contacts positioned in from one end, a plug member comprising a fuse insertable into the other end of said sleeve and having terminal contacts for engageinent with said stationary contacts and a releasably mounted terminal member positioned beyond said stationary contacts and free to be blown o by blowing of the fuse, the sleeve member extending beyond said releasably mounted terminal member to form a straight unobstructed opening for the expulsion of said terminal member.

3. In av cut-out, a plug member, and -a cooperating socket member, said socket member comprising a sleeve of insulation open at both ends and having stationary contacts therein, said plug member comprising a tube of insulation, contacts on' said tube adapted to engage with said stationary'contacts, a fusible element in said tube, a terminal member at the end of said tube in conducting relation with said fusible element, said plug member adapted for insertion into one end 'of said sleeve, the other end of said sleeve having a straight unobstructed opening to atmosphere to permit the expulsion of said 4terminal member 'upon the blowing of said fusible element. 4

4. In combination, a plug member comprising a tube' of insulation, terminal contacts on said tube, a fusible element in said tube, spring means connected to one end of said fusible element, the other end of said prising a tube of insulation, contact ferrules on said tube, a fusible element in said tube, spring means connected to one end of said fusible element, the other end of said fusible clement being connected to a relcasable ter` minal member closing olf one end of said tube and havingconnection with the adjacent contact ferrule, a socket member comprising a sleeve of insulation having stationary contacts therein for engagement with the contact fel-rules, said plug member adapted to be inserted into one end of said sleeve, the other end of said sleeve having an unobstructed axial opening to permit the discharge of said releasable terminal member when the fusible element blows.

6. In combination, a socket member and a co-operating plug member adapted to be inserted in the upper end of the socket member, said socket member comprising a hollow sleeve. of insulation having stationary contacts therein, an air expulsion fuse carried by said plug member comprising a tube of insulation having contact ferrules thereon adapted to engage with said stationary contacts, a fusible element in said tube, a spring in said tube tending to separate said fusible element, a releasable cap closing the bottom of said tube and having contact with the lower contact ferrule, said fusible element being connected to saidrelea'sable cap, the lower end of Asaid sleeve having a straight unobstructed opening to atmosphere to permit the expulsion of said releasable cap upon the operation of said fuse.

7. In combination, a socket member and a cooperating plug member adapted to be inserted into the upper end of said socket member, said socket member comprising a hollow sleeve of insulation having station` ary contacts therein, a fuse carried by said.

llll

' said sleeve by the blowing of Said use.

r17. In a cut-out, the combination of a socket member, and al (so-operating plug member adapted to be inserted'into the upper end of said socket member, said-.socket member comprising a pair of stationary contacts therein, the plug member comprising a tube of insulation having contact ferrules thereon adapted to engage with -Usaid stationary contacts, a pair of fuse terminals in said tube, a fuse connecting said fuse terminals, a spring tending to separate said fuse terminals, a member surrounding said fuse for sealing said fuse from the atmos-l phere, a releasable end cap carried by said tube adjacent its lower end, said end cap connecting one of said fuse terminals 'with the lower contact ferrule, the lower end of said socket having a straight unobstructed opcningto atmosphere to permit the expulsion of said latter fuse terminal and said end ca-p under the gas pressure generated by the blowing of said fuse.

18.' In a device of the class described, a sleeve open at both ends, and a fuse plug insertable in one end, said plug having a cap arranged to be blown out of the other end of said sleeve when the fuse blows.

19. In a device of the class described, an insulating sleeve, terminals in said sleeve, fusible means connecting said terminals, resilient means for drawing one terminal in one direction, and a support for the other terminal adapted`to be blown in the other direction when rupture of said fusible element occurs violently.

20. In a device of the class described, a

` sleeve, a fused plug insertable in one end of said sleeve, a cap on the end of said plug, and an indicator on said cap projecting from the other end of said sleeve.V

21. In a device of the class described, a sleeve, a fused plug insertable in one end of said sleeve, and a cap on the end of said plug adapted to beblown out of the` 'other end of said sleeve by violent rupture of the fuse in said plug. i

22. In a device of the 'class described, a"

sleeve, a fused plugiiisertable in one end of said sleeve, a cap on the end of said plug adapted to be blown out of the Vother end of said sleeve by violent rupture of the fuse in said plug, an indicator on said cap projecting from the other end of said sleeve, and meansfor extinguishing the arc upon gentle Arupture of said fuse without blowing out nal member closing one end of said tube, the i other end of the tube being reduced, a ferrule on said reduced end, a terminal cap sprung in the end. of said ferrule and closing the end of the tube, a fuse connected between the ixedly mounted terminal membei' and the terminal cap, said cap being free to be blown out by pressure generated in the tube by blowing of the fuse.

24. In an air expulsion lfuse, the combination of a casing open at one end,a sleeve terminal at said open en'd 0f said casing, a second terminal at the other end of said casing, a connector comprising a central portion having angularly displaced side arms engaging the inside of said sleeve, a fuseV connected between said second terminal and the central portion of said connector, and spring means for placing said fuse under tension.

25. In an air expulsion fuse, the combination of a casing, a terminal at one end of said casing, a sleeve terminal at' the other end ot' said casing, a fusible link within said casing and connected at one end with said first terminal, a connector attached through its cen-Q ter to the other end of said link and having springy cylindrical segmentsadapted to engage the inside of said sleeve terminal, and spring means for placing said link under tension.

26. In an air expulsion fuse, the combination ofan insulating shellwith metallic end terminals, one of said terminals being sealed and the other unsealed,a fusible link within. said shell and connected at one end to said sealed terminal, a sheet metal connector engageable through its center with the other end of said' link and having segmental ends adapted to engage the inside of said unsealed link under tension. n 27 In an expulsion fuse comprisinfr a casterminal, and spring'means for placing said ing having a terminal at each end, a If-,use bemounting to which one end of said fuse is' connected, characterized in that the releasable mounting comprises a flexible member having side arms, adapted to engage and bear against the sides 4 to Ibe released when said tensionY isreleased upon the blowing 'of the fuse. y

2S.`In an expulsion fuse comprising a casing having a terminal at each end, a fuse betweensaid terminals under spring tension,- one of said terminals having a releasable mounting tovwhich one end of said fuse is connected, characterized iii that the terminal having the releasable mounting is in the form ofthe terminal and adapted,

of a sleeve, and in that the releasahle mounting is in the form of a iiexible" metal cap Within the sleeve terminal.

29. In a. fuse a containing sleeve of insulation having metal terminals, one of said terminals comprising u metal sleeve mounted on the insulating sleeve and extending he-y yond the end thereof to provide :i cylindrieel `metal bore, a fusible link within the insulating sleeve, :i metal connector having spring arms bearing against the inside of the 1 metal sleeve to malte Contact therewith and to support the connector slidably in the metal sleeve, said connector being electrically oon- ,neoted to one end of the fuse, said connector,

upon blowing of the fuse being adapted to be expelled from the outer end of the metal sleeve.

In Witness whereof, I hereunto subscribe my naine this 9th day of November, 1928.

NICHOLAS J. CONRAD. 

